Reversible-circulation internal-fan kiln



Sept. w, .n 924. I 1,,@

R. THELEN REVERSIBLE CIRCULATION INTERNAL FAN KILN 7 Filed July 12;, 1925 2 Sheets-Shae: 1

=INVENTOR. ROLF THELEN A TTORNEY-f R. THELE-N anvaasmm cmcumnou INTERNAL FAN KILN 1 Filed July 12 1923 2 Shams-sa a 2 oodoooooooooowL- INVENTOR. ROLF THELEN ATTORNEYK.

Patented Sept. 30, 1924.

nnrra srarns ROLF THELEN, F M ADISON, WISCONSIN, DEDICATED, BY HESNE ASSIGNMENTS, TO THE CITIZENS OF THE UNITED STATES OF AMERICA.

REVERSIBLE-CIRCULATION INTERNAL-FAN KILN.

Application filed July 12, 1923. Sex-121.1%. 651,071.

(FILED UNDER THE ACT OF MARCH 3, 1883, 22 STAT. L., 625.)

To all whom it may concern:

Be it known that 1, Row THELEN, a citizen of the United States of America, and an employee of the Department of Agricultnre, residing in Madison, Wisconsin (gwhose post-oflice address is Madison, Wisconsin), have invented a new and Improved Reversible-Circulation Internal-Fan Kiln.

This application is made under the act of 9 March 3,-l8 83, chapter 143 (22 Stat. 625), and .the'rinvention herein described and clalimedmay'be used by the Government of the United States, its oflicers' and employees, I and by any person in the United States without the payment to me of any royalty thereon. I hereby dedicate the same to the free use of the Government and the people of the United States. I p

. Myinvention consists in an improvement in the design of forced circulation kilns or chambers for drying and conditioning lumher or similar material. However, its use is not limited to wood or wood produdts. It co'nsists in the adaptation of fans of the disk type, or similar types, to the production of a unique internal circulation of air and the vapor in the kiln combined with the production and regulation of the heat and the humidity within the kiln.

1 and 2. Figure 1 represents a longitudinal vertical section, and Figure 2 represents a transverse vertical section.

The principal feature which I claim as novel and an improvement over existing "kilns is the use and arrangement of the fans and the air distributing system. This arrangement is such that a very fast and uniform circulation of air and vapor through the pile of lumber may be secured.

and permits the periodic reversal of the direction of the air movement. by simply reversing the direction of rotation'of the fans. The air distributing system provides a very uniform flow of air throughout the length of the kiln and eliminates the non-uniformity of drying, which is one ofthe commonest troubles experiermed in the ordinary kiln. The arrangement of the fans upon a single shaft extending throughout the length of the kiln rovides a simple means of producing a brisk circulation; and the elimination of comparatively small ducts such as those This invention is illustrated in Figures used in external blower kilns reduces very materially the work required to produce a given circulation. The differences in air pressure required in the operation of this kiln are much smaller than those ordinarily required in kilns employing centrifugal blowers, and the disk fans operate very efficiently at these low pressures. It is pos sible, therefore, by the use of this invention to produce a very great and uniform circulation of air and vapor within the kiln with a very small expenditure of power.

' While it is obvious that there are many possible ways in which the use'of internal fans can be adapted to drying kilns of different types, this invention is limited to kilns in which the lumber is flat cross piled and in which a single row of fans is employed. It is further limited in that adjacent fans are of opposite pitch.

Any well-known means of heating the air and the Vapor in the kiln may be used in conjunction with this invention. v When steam pipes are used they may be arranged beneath the lumber piles or in any other convenient manner. Any convenient form and arrangement of heaters may be used.

The drawings show and the specification describes steam jet pipes for increasing the humidity, and air inlet fines with suitable dampers for decreasing the humidity.

'While the drawings show and the specification describes specific means for heating the air and the vapor in the kiln and for regulating the humidity of the air in the kiln, this invention is not limited specifically to the arrangements described, but may make use of any other suitable and well-known means for accomplishing the same purposes. WVhile the drawingsillustrate and the specification describes a specific form of flat cross piled lumber, the invention is not limited to this particular form since it is equally applicable to all other forms of fiat cross piling and to other well-known methods 'ofarranging the lumher on the trucks. v

Referring to Figures 1 and 2 which are correspondingly lettered AA. and YY are air chambers in the lower portion of the 'kiln. W hen the direction of air circulation ing the circulation.

fans are preferable. .Any type of fan, howhumidityof the air in the kiln.

the nature of plenum chambers, and the air chambers YY are under a slight vacuum, being in the nature of vacuum chambers. When the direction of circulation is re- -versed,. air chambers AA become vacuum chambers and air chambers YY become plenum chambers. BB are the fans produc- Straight-bladed disk ever, in which the reversal of the direction of rotation of the fan produces a reversal in the direction of the flow of air current passing through the fan can be used. Ad- ]acent fans are of opposite-pitch sothat they blow toward each other when the rotation is in one direction and away from each other when it is in the opposite direction. Figure 1 shows the fan farthest to the left to be right-handed and the one next to it left-handed. The third and fifth fans from the left are also right-handed, and the second, fourth, ,andsixth left-handed. When the flow of air is as indicated in Figure 1 all of the fans blow into the respective air chambers A, drawing airfrom the respective air chambers Y. When the direction of rotation of the fans is reversed, the fans will all blow into the respective air chambers Y, drawing from the-respective air chambers A. G is the shaft upon which the fans are mounted. Provision is made to take care of the expansion and contraction of this shaft with changes in tempera ture in the kiln. DD are air inlet dampers used to regulate and to control the amount of air entering the" kilns from the outside. coils illustrated in the drawings and described in the specification are of the header type. This invention is not, however,

limited to this type since any common or well known type may be adapted to it. FF are the steamjet pipes used to increase the Those in theair chambers AA may be used when the direction of flow of the air current is as indicated in Figure 1. When the direction of flow is reversed, those jet pi es in air chambers YY may be used. G lumber supporting trucks. HH are the shaft hangers. II are bearings for the shaft'C. JJ are the tracks upon which the lumber-supporting trucks run. The invention is not specifically limited to'the form-and arrangement of lumber-supporting trucks, tracks, and track supports illustrated since any well-known method of supporting the lumber may be used without influencing in any wav the efficiency or operation of the kiln. KK are the walls of the drying chamber. LL is the lumber to be dried. MM are track supports. N is the shaft pulley. 00 are air outlet'dai per'sfor controlling the amount of air be- Elfi are the heating coils. The

are the' ing exhausted from the kiln. P is a belt passing over the pulleys N and Q. Q is the motor pulley. R is the motor which furnishes the power to drive the fans. is a switch for controlling the speed and direction of the rotation of the motor armature. While the drawings show and the specification describes an electric motor, any other suitable driving means may be used. TT are air outlet fines in which the dampers 00 are fitted. VV are the air chamber partitions. These partitions extend across the kiln from side wall to side wall and serve to separate air chambers AA from air chambers YY. Suitable housings or openings are provided in these air chamber artitions for the fans BB. WW and X and between the lumber on the lumber-supporting trucks. While the drawings illustrate and the specification describes parallel-sided air passages, air passages of other common and well-known shapes may be used. ZZ are diffusers, the purpose of which are air passages adjacent to fusers form the only passage between the air chambers and the air passages.

The operation of the kiln is briefly as follows: The lumber is placed in the kiln, the doors and all of the dampers are closed, and the kiln is started. Steam is turned into the coils and one set-of steam jets is turned on. Suitable regulating devices are provided to control and regulate. the supply of steam to the heating coils and the supply of steam to the steam jets. If it is found impossible to reduce the humidity to the desired point with the. steam jets all turned off, the dampers DD and 00 are opened to allow fresh air to enter and moist air to escape. These dampers are adjusted .so that a humidity below that desired will be'secured. The steam jets may then automatically supply a sufiicient amount of steam to hrin the humidity up to the desired point. I? the direction of the rotation of the motor, the shaft, and the fans is such as to cause the air flow to be as indicated in Figure 1, the air and vapor will pass upwardly out of the air chambers AA, throu h the difi'users ZZ, into the air passages AX, thence laterally through'LL, the piles of lumber to be dried, into the air passages \VV, downward through these passages, and through the diffusers ZZ in the tops of the air chambers YY, through these .air chambers into, the fans BB, and thence into the air chambers AA. The resistance to the flow of air caused by the difl'users ZZ assists in maintaining a slight plenum 1n the air chambers AA and producing a uniform distribution'of;the air rections tends to eliminate in large measure the lack of uniformity in air distribution resulting from the velocity of the air issuing from the fans.

It is well understood that when the circulation. of theair in the kiln is continuously in one direction, that portion of the pile at which the air enters will dry more rapidly than the opposite side since the air in its passage through the lumber. picks up moisture and thus reduces its drying capacity. Tooveroome this defect, the direction of rotation of the fans may be reversed, thus reversing the direction of the motion of the air through the lumber piles. This may be done periodically every two or three days or oftener, the exact eriod being determined by the condition of the lumber in the kiln.

he direction of the air travel is then as follows: The air passes from the air chambers YY upward throu h the .difi'us'ers ZZZ at the tops of these air 0 members into the air assages WW, from these laterally through EL, the lumber to be dried, into the air passages XX, downward through these air passag:- through the diffusers ZZ, on top of the air chambers AA, into the air chambers AA, thence throu h the fans BB into the air chambers Yl Having fully described the principles of this invention and the manner in which they can be embodied in a dry kiln, I claim as original: 1. In a dry kiln arranged for flatwise cross piling: a series of fans in which adjacent fans are of opposite pitch; a shaft on which the fans are mounted for rotation; and means for rotating said shaft in either direction to cause reversal of the circulation of the air and vapor in said kiln.

2. In a dry kiln arranged for flatwise.

cross iling: a series of fans in which adjacent ans areof opposite pitch; a shaft; on which the fans are mounted for rotation; means for rotating said shaft in either direction to cause reversal of the circulation of the air and vapor in said kiln; and an air distributing system comprising air chambers and diffusers.

3.111 a dry kiln arranged for fiatwise cross piling: a series of fans in which adjacent fans are of opposite pitch; a shaft on which the fans are mounted forrotation; means for rotating said shaft in either direction to cause reversal of the circulation of-the air and vapor in said kiln; an air distributing system comprising air chambers and difi'users; and dampered air inlet fines "and dampered air outlet fines.

4. In a dry kiln arranged. for fiatwise cross piling: a series of fans in which adjacent fans are of opposite pitch; a shaft on which the fans are mounted for rotation; means for rotating said shaft in either direction to,cause reversal of the circulation of the air and vapor in said kiln; an air distributin system comprising air chambers and di users; dampered air inlet fines and -dampered air outlet fines; and means for heating the kiln andits contents.

5. In a dry kiln arranged for flatwise cross piling a series of fans in which adjacent fans are of opposite pitch; a shaft on Which the fans are mounted for rotation;

means for rotating said shaft in either di v rection to cause reversal of the circulation of the air and vapor in said kiln; an air distributing "system comprising air chambers and diffusers; dampered air inlet lines and dampered air outlet flues; means for heating the kiln and its contents; and means for huinidifying the atmosphere in the kiln.

6. In a dry kiln arranged for fiatwise cross piling: two series of air chambers, the chambers of one series alternating with/those of the other series.

7 In -a dry kiln arranged for flatwise cross piling: an air distributing system comprising two series of air chambers, the chamers of one series alternating with those of the other series, and diffusers.

'8. In a dry kiln arranged for fiatwise cross piling; an air distributing system comprising two series of air chambers, the chamers of one series alternating with those of the other series, and diffusers; and means for producing a slight vacuum in one series of air chambers simultaneously with a slight plenum in the other series of air chambers.

9. In a dry kiln arranged for fiatwise cross piling: an air distributing system comprising two series of air chambers, the chamers of one series alternating with those of theother series, and diffusers; and means for producin a slight vacuum in either *series of air cham erssimultaneously with a slight plenum in the other series of air chambers.

10. In a dry kiln arranged for flatwise cross piling: an air distributing system comprising two series of. air chambers, the chambers of one series alternating with those of the other series, and diffusers; means for producing a slight vacuum in one series of air chambers simultaneously with a slight plenum in the other series of air chambers; and. dampcred air inlet fines and air outlet flues.

11. In a dry kiln arranged for flatwise dampered the other series, and diffusers; means for producin a slight vacuum in either series of air chamb ers simultaneously with a slight plenum in the other series of air chambers; and dampered air inlet fiues and dampered air outlet fines.

' 12.1n a dry kilnarranged for flatwisc cross piling: an air distributing system comi tlampered'air inlet flues andidampered air outlet flues; and means for heating the kiln and its contents.

13. In a'dry kiln arranged for fiatwise cross-piling: an air distributing system comn-ising two series of air chambers, the chambers of one series alternating with those of the other series, and diffusers; means for producing a slight vacuum ineither series of air chambers simultaneously with a slight plenum in the other series of air chambers; (tampered air inlet fines and dampered air outlet fines; and means for heating the kiln and its contents.

14. In a dry 'kiln arranged for flatwise outlet fines; means for heating the kiln and its contents; and means for humidifying the atmosphere in the kiln.

15. In a dry kiln arranged for flatwisc cross piling: an air distributing system comprising two series of air chambers, the chambersot' one series alternating with those of the other series, and (lill'users; means for producin a slight vacuum in either series of air chainiers simultaneously with a slight plenum in the other series of air chambers; dampered air inlet flucs and dampered' air outlet fines; means for heating the kiln and its contents; and means for hun'iidifying the at mosphere in the kiln.

ROLF THELEN. 

